# Tag Info

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Surface gravitational acceleration on an object with mass $M$ and radius $R$ is given by $$g = \frac{GM}{R^2} \propto G\rho R$$ where $\rho \propto M/R^3$ is the density of the object. Titan is larger than Earth's Moon, so it must be less dense. Wikipedia confirms: $R_\text{Titan} = 1.5 R_\text{Moon}$, but $\rho_\text{Moon} = 3.34\rm\,g/cm^3$ while ...

5

A rough formula for the exponential scale height of the atmosphere is $$h = \frac{kT}{\mu m_u g},$$ where $T$ is the temperature of the gas, $m_u$ is an atomic mass unit, $\mu$ is the number of atomic mass units per particle and $g$ is the surface gravity, with $g = GM/R^2$. For a typical neutron star with $R=10$ km, $M= 1.4M_{\odot}$, we have ...

3

Both the radiation and gravity follow an inverse square law, so there is no "horizon" at which gravity would overcome light radiation, they both get weaker at the same rate. Radiation pressure affects smaller objects disproportionately. This is one factor in the formation of comet tails: dust and gas is pushed away from the heavier nucleus, which is ...

3

While I'm lacking the formulae, the applicable surface area of a body would have to be great enough, and it's density low enough that it's gravity remains below that threshold. So a smaller body is much more likely. If you think about it, most dust from near the sun gets pushed out by the pressure. There wouldn't be a specific point where you would get the ...

3

In some models of quantum gravity there are 10 dimensions. 7 of these are curled up and very small. Gravity is a force it is not a dimension. If these models of quantum gravity is correct then we do live in these 10 dimension. If these models are correct then we do live in "hyperspace", but only 3 dimensions are macroscopic. Dimensions don't govern the ...

2

The comments from @userLTK, and @Lacklub are correct. Lets assume there is an object of radius $R$ and mass $M$, from a Newtonian point of view, if you are at another radius $r$, such that $r > R$, then there is no difference in the gravitational field experience by an object at $r$ if the mass spread across a shell of radius $R$ or if its concentrated ...

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